<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style>
    
  </style>
</head>
<body>
  
</body>
<script>

  function fn(){
    var year = 2023;
    if(year % 4 === 0 && year % 100 !== 0 || year % 400 === 0){
      console.log("是")
    }else{
      console.log("不是")
    }
  }

  function fn2(){
    for(var i=1; i<=9; i++){
      for(var j=1; j<=i; j++){
        document.write( j + "*" + i + "=" + i*j + "&nbsp;&nbsp;" );
      }
      document.write("<br>")
    }
  }

</script>
</html>